Planing boat



R. S. RAE

PLANING BOAT Sept. 30, 1969 2 Sheets-Sheet. 1

Filed Jan. 11, 1968 R. S. RAE

PLANING BOAT Sept. 30, 1969 2 Sheets-Sheet 2 fim/pm 1 ,9 5, R45

Filed Jan. 11, 1968 United States Patent 3,469,549 PLANING BOAT Randolph S. Rae, 858 Production Place, Newport Beach, Calif. 92660 Filed Jan. 11, 1968, Ser. No. 697,043 Int. Cl. B631) 1/20 US. Cl. 114-665 6 Claims ABSTRACT @F THE DISCLOSURE This invention relates to a planing boat and more particularly to a low-drag, high-performance planing boat having three bottom planing surfaces consisting of a forward and two aft planing surfaces.

In a conventional, single hull planing boat, optimum planing at high speed would be at the rear end of the hull at an optimum planing angle of about Since it is not practical from stability consideration to have the center of gravity at the rear end, reduced planing angles, such as about 1 to 2 degrees, must be accepted resulting in increased drag during high speed planing. In other words, if a single hull planing boat were to utilize the most efficient planing angle of about 5, this would require the boat to ride On the very aft end surface and would put the center of gravity of the boat ahead of the forward point of contact with the water so that there would be a loss of pitch stability. Thus, in order to place the point of contact with the water forward of the center of gravity, the plane angle is reduced from the most efficient angle of about 5 to an angle of 1 to 2 degrees. With this reduced planing angle, there is a much greater wetted area of the boat during planing which produces considerably more skin friction.

A three hull planing boat is illustrated in US. Patent D. 197,869 issued to the present inventor and this boat utilizes one forward and two aft planing points. The center of gravity is Well forward of the two rear planing points and the three planing surfaces can have an angle to the water of about 5 to produce minimum drag at the designed planing speed. In this configuration, however, the low speed drag and transition drag are excessive because the hulls are short and ride low in the water before planing. This results from the fact that the short hulls immerse considerably in the water to provide enough displacement to support the boat at rest and at low speeds.

The three planing hulls of the planing boat of the present invention are integrated into an essentially triangular superstructure so that the planing surfaces can be placed at a planing angle which results in minimum drag. The front hull extends aft toward the rear end of the boat and an after body is located between the aft end of the front hull and the rear of the boat. The two back hulls are lengthened in the forward direction as far as possible so that they extend to and beyond the aft end of the front hull and provide for acceptable low speed and transition drag. Break away of water at the aft end of the front hull is provided during planing to prevent the water from Patented Sept. 30, 1969 clinging to the bottom and producing additional drag. This break away can be accomplished in numerous ways, such as by a step or sharp angular surface at the aft end of the front hull. The step is located forward of the center of gravity in order to distribute the weight of the boat to the three planing points. By extending the back hulls forwardly as far as possible, the wetted length of the back hulls is increased before planing sets in and the low speed drag characteristics are improved. The back hulls can have nearly a constant planing angle of about 5 and the front hull can have a planing angle of about 5 at its aft end, before it flares upwardly and forwardly toward the bow. Thus, the boat of the present invention has all the desirable characteristics of a three hull boat, such as stability in pitch, roll and yaw, and also provides a substantial reduction in low speed drag by extending the back hulls forwardly and streamlining behind the front hull. The effect of these features is to provide a boat having a low transition and displacement drag because of the increased low speed wetted surface of the boat. Because the center of gravity is preferably located centrally of the planing points, the engine can be located forward to provide a more spacious, compact cockpit extending to the rear transom. The front hull can be symmetrical about the vertical center plane of the boat while the back hulls are located in the opposite sides of said center plane.

It is therefore an object of the present invention to provide a planing boat having three planing hulls integrated into a single structure, said hulls comprising a front hull and two back hulls.

Another object of the invention is to provide a planing boat having three planing hulls, each of which has a substantially optimum planing angle in order to produce very low drag at high planing speeds.

Another object of the invention is to provide a planing boat having three planing hulls comprising a front hull followed by an after body and two back hulls commencing at the rear end of the boat and extending forwardly to increase the wetter length of the back hulls before planing sets in.

Another object of the invention is to provide a planing boat which planes on three points and has excellent stability in the pitch, yaw and roll planes.

Another object of the invention is to provide a planing boat having three planing hulls and a center of gravity located well forward of the rear of the boat.

A further object of the invention is to provide a planing boat having low drag in the planing condition and acceptable low level drag in the pro-planing condition.

These and other objects of the invention not specifically set forth above will become readily apparent from the accompanying description and drawings in which:

FIGURE 1 is a side elevational view of the planing boat showing the engine and propeller in phantom lines;

FIGURE 2 is a bottom plan view along line 2-2 of FIGURE 1 showing the front hull and the two back hulls;

FIGURE 3 is a front elevational view along line 3-3 of FIGURE 1;

FIGURE 4 is a rear elevational view along line 44 of FIGURE 1;

FIGURE 5 is a partial side elevation similar to FIG- URE l of a modification having a series of suction openings located aft of the front hull;

FIGURE 6 is the front elevational view similar to FIG- URE 3 of a modification in which the front hull is pivotally mounted;

FIGURE 7 is a side elevational view along line 77 of FIGURE 6 showing the spring device for the front hull;

FIGURE 8 is a vertical section along line 88 of FIG- URE 7 illustrating the guided front hull;

FIGURE 9 is a side elevational view of the planing boat carrying sails; and

FIGURE 10 is a bottom plan view along line 10-10 of FIGURE 9 showing the keel and rudders for the sailboat.

Referring to the form of the invention chosen for illustration in FIGURES 14, the planing boat consists of an essentially triangular shaped structure having side deck portions 16 and 17 extending between a front deck portion 18 and a rear deck portion 19. An upright, transverse bulkhead 20 is located centrally of the boat and is cut away to form a mounting edge 21 for supporting engine 22 which drives propeller 23. Sides 24 and 25 of the boat terminate at the forward end in the how 26 and connect at the aft end with the rear transom 27. Also, a windshield 28 is located at the rear end of the top deck portion 18 and the cockput 33 extends between the bulkhead 20 and the rear transom 27. Propeller shaft 29 extends from the engine 22 through shaft log (or gland) 30 located in a bottom opening in the boat and through a bearing 31 carried by propellor bracket 32 extending from the bottom of the boat.

The bottom of the boat comprises a front hull 34 and two back hulls 35 and 36. The sides and 41 of the front hull 34 taper downwardly to an apex (keel) line 42 which extends from the aft end of the hull to the bow. The sides 40 and 41 are symmetrical about the vertical, center, longitudinal plane of the boat so that the apex line 42 lies in this plane. The bulkhead 20 forms a step portion 45 at the aft end of the front hull 34, and an after body 47 extends rearwardly of the front hull. Sides 48 and 49 of the body 47 slope downwardly to an apex (keel) line 50 and extend to abut the bulkhead 20 at a location above the front hull 34 in order to form the step portion 45. The apex line of the after body 47 lies in the center, longitudinal plane of the boat and the sides 48 and 49 of the after body are symmetrical about this plane. The shaft log 30 is located at the apex line aft of the step 45. Back hull 35 has sides 51 and 52 which slope downward to an apex (keel) line 53 and back hull 36 has sides 54 and 55 which slope downwardly to an apex (keel) line 56. The apex line 53 and sides 51 and 52 of the back hull 35 extend from the bulkhead 20 rearwardly to the back transom 27. Also, the side 51 extends forwardly of bulkhead 20 and connects with stepped edge of the front hull 34. In a similar manner, apex 56 and sides 54 and 55 of back hull 36 extend between bulkhead 20 and rear transom 27 and side 54 also extends forwardly of the bulkhead 20 to meet the stepped edge 61 of the front hull 34. As illustrated, the back hulls 35 and 36 are located symmetrically on opposite sides of the center longitudinal plane of the boat and on opposite sides of after body 47 so that side 52 of hull 35 and side 55 of hull 36 meet sldes 48 and 49, respectively, of the body 47. With the engine 22 installed on the bulkhead 20, propeller 23 drives the boat forwardly and the boat is steered by a rudder 64 having a shaft 65 rotatably mounted in the transom 27 by bearings 66 and 67. A steering arm 68 extends through an opening on the transom and can be connected to any suitable steering mechanism. Rudder 65 is located behind propeller 23 and both are located at the longitudlnal center plane of the boat. As illustrated, the front hull is substantially one-half the maximum width of the boat and is substantially one-half the total length of the boat. However, the width and length can be varied somewhat without substantially changing the performance of the boat.

When the boat 15 is at rest or moving at slow speed, it rides to the depth of the water line W (see FIGURES 1 and 4). As the speed of the boat is increased, the boat will commence to plane and during planing, it will ride in the water at a depth illustrated by the line X. The angle between apex lines 42, 53 and 56 and the horizontal water line X is defined as the planing angle and the optimum planing angle is about 5. The apex lines 53 and 56 of he back hulls have a planing angle of about 5 over their entire length. The apex line 52 of the front hull has the same angle over the rear portion which engages the water during planing and the angle then increases as it approaches bow 26. Thus, during planing the apex line 42 of the front hull and the apex lines 53 and 56 of the rear hulls form an optimum planing angle with the water line X of approximately 5. The portion of the front hull aft of the dotted line 34a and the portions of the back hulls aft of the lines 35a and 36a of hulls 35 and 36, respectively, are the only portions of the bulls which engage the water during planing so that there is minimum drag during high speed planing operation. The center of gravity, designated cg in FIGURES 1 and 2, is located between the three planing areas 34a, 35a and 36a so that all three areas have about the same planing angle and ride to about the same depth. Therefore, the planing angle of the boat hulls do not have to be reduced from the optimum value, as in single hull planing boats.

During planing, the step portion 45 aft of the front hull causes the water to break away at the aft end of the front hull in order to keep the water from sucking the boat down. By utilizing an optimum planing angle of about 5, there is a minimum of drag during high speed operation since there is minimum contact with the water and the surfaces of the individual hulls have an optimum lift to drag ratio. By having the front hull extend rearwardly a considerable distance and having the back hulls extend forwardly to and beyond the front hull, the wetted length of the forward and back hulls is sufficient to provide acceptable low speed drag and transition drag before planing sets in. Since the step 45 occurs forward of the center of gravity, the weight of the boat is distirbuted on the three planing points. Of course, the amount of wetted area of each hull would depend upon the location of the center of gravity. The high speed drag at planing is reduced to a minimum since the planing surfaces have a high aspect ratio, i.e. a considerable beam and a small wetted area.

As illustrated in FIGURE 5, the break away of the water behind front hull 34 can be obtained by having after body 47a connect with the front hull at a reduced angle and locating a series of openings 70 in the after body just aft of connecting line 71 between the after body and the aft end of the front hull. The openings 70 connect to a manifold 72 located inside the boat and the manifold is connected to atmosphere by a passage 73. Thus, when the boat commences to plane, air will be sucked through the passage 73 and opening 70 into the water in order to cause break away behind the front hull and prevent water from sucking down on the boat. In the absence of openings 70, water break away will be produced aft of the front hull by a sharp enough step to cause the break away.

Another modification of the invention, illustrated in FIGURES 6-8, has a front hull 34 which is constructed separately from the boat and moves in a compartment in the boat defined by inner bulkheads 76 and 77 (see FIGURE 8) which extend between the bow and the cockpit. The hull 34 is pivotally connected to the bow 26 by means of a pivot pin 79 and engine 22 is supported on a bulkhead 78 at the rear of the hull in the same manner as on the edge 21 of the bulkhead 20 in the prior embodiment. The front hull 34 has the side surfaces 40 and 41' terminating in an apex line 42' and also has side panels 80 and 81 which are guided by bulkheads 76 and 77, respectively, as it moves relative to the boat about the pivot pin 79. A channel bar 85 extends between the side panels 80 and 81 of the hull 34 and carries a plurality of spaced pins 86. Also, the under side of the top deck portion 18 carries an angle iron 87 mounting a plurality of pivot pins 88 opposite to pins 86. Between each pair of pivot pins 86, 88 extends a combination spring and shock absorber device 90 which normally positions the hull 34 in the same position with respect to the boat as illustrated in FIGURE 1. However, in

rough water, the device attempts to have the surface of hull 34 follow the water in order to reduce the pounding of the bottom of the boat against the waves. In other words, the device 90 has a load-force characteristic which normally locates the hull in a normal load supporting position. However, should the load supported by the hull reduce, the hull would move outwardly and should the load supported by the hull increase over the normal load, it would move inwardly thus causing the hull to follow the surface of the water. Actuators of this type are well known in the art and it is not considered necessary to go into the structure of such spring and shock absorber devices.

Another modification of the invention in the form of a sailboat is illustrated in FIGURES 9 and 10. A mast 92 is secured to the top deck 18. Also, a pair of rudders 93 and 94 are pivotally mounted in bearings 95 and 96, respectively, and have link arms 97 and 98, respectively, which are connected by a link 99. The arm 98 and the link 99 can be manually moved by the tiller 100 in order to move the rudders and steer the sailboat. A keel 102 can be inserted through a slot 103 in the bottom of the boat and the sides 48' and 49" of the after body 47' go forward to meet the bulkhead and provide a step portion 45'. The mast 92 carries a main sail 105 and a jib 106. When the sailboat gains sufficient speed, it will plane on the three planing surfaces even though it may be rolled over about roll axis because of the action of the wind on the sails so that one side hull has a greater surface in contact with the water than the other side hull.

The present invention provides a boat consisting of three planing hulls integrated into an essentially triangular superstructure and the planing surfaces are at an angle which results in a minimum drag of the boat at planing speed. Minimum drag for the boat of the present invention of one-tenth of the weight is indicated as compared with something on the order of two-tenths of the weight for a single hull boat. The boat has acceptable low speed drag characteristics because of the presence of an after body behind the front hull and because the side back hulls are extended forward as far as practical so as to increase the wetted length of the rear hulls before planing sets in. The boat structure provides the following characteristics: (a) very low high speed drag (b) acceptable low speed displacement drag (c) acceptable low speed transition drag (d) excellent stability in the pitch, yaw and roll planes (e) aerodynamic stability of the boat when it is out of the water. As a result, the boat requires less power at planing speed than present planing boats.

It is understood that all types of inboard and outboard power units can be utilized using one or more engines and one or more propellers. Conventional engines driving a fan or jet engines or fan jets can be utilized to obtain propulsion by reaction force. The power units could be located rearwardly in the boat and compensation made to prevent the shift of the center of gravity too far rearwardly. With the engine located in the front hull, an out drive can be located directly behind the step at the aft end of the front hull instead of utilizing a propeller shaft extending to the rear of the boat. The three hulls can be connected by various types of constructions, other than an essentially triangular shaped superstructure. Also, while an after body with angular sides is preferred, the after body can have other shapes, such as flat, and the shape and length of the back and front hulls can also be varied. In the form of FIGURE 5, the openings 70 could be connected to the engine exhaust manifold instead of to the atmosphere so that exhaust gases would be forced outwardly through the openings to result in breakaway of flow from the front hull. Various other modifications are contemplated by those skilled in the art without parting from the spirit and scope of the invention as hereinafter defined by the appended claims.

What is claimed is:

1. A planing boat comprising:

a front hull located at the bow of the boat and substantially less than the width of the boat;

first and second back hulls located at the rear of the boat on opposite sides of the longitudinal, vertical, center plane of the boat and extending forwardly at least as far as aft edge of said front hull;

said front and back hulls having a substantially optimum planing angle during planing to provide low drag at high speed;

said back hull having a wetted pre-planing area sufiiciently large to provide acceptable low speed displacement and transition drag;

each of said front and back hulls having side surfaces sloping upwardly from an apex line;

the apex lines of said back hulls extending from the aft end of said boat to the aft end of front hull;

one side surface of each of said back hulls extending to the aft end of said front hull; and

the other side surface of each back hull extending forwardly beyond the aft end of said front hull toward said bow of the boat.

2. A planing boat as defined in claim 1 having an after body extending from the aft end of said front hull toward the aft end of the boat; and means for causing break away of water at the aft end of said front hull, said after body comprising side surfaces sloping toward an apex line at said center plane of said boat and extending rearwardly from the aft end of said front hull.

3. A planing boat as defined in claim 2 wherein said one side surface of each back hull extends to a side surface of said after body.

4. A planing boat as defined in claim 2 wherein said means for causing break away of said water at the aft end of said front hull comprises an upward step at the aft end of said front hull, said side surfaces of said after body abutting said step above the rear of the apex line of said front hull.

5. A planing boat comprises:

a front hull located at the bow of the boat and substantially less than the width of the boat;

first and second back hulls located at the rear of the boat on opposite sides of the longitudinal, vertical, center plane of the boat and extending forwardly at least as far as aft edge of said front hull;

said front and back hulls having a substantially optimum planing angle during planing to provide 10W drag at high speed;

said back hull having a wetted pre-planing area sufficiently large to provide acceptable low speed displacement and transition drag;

means for pivotally connecting the front end of said front hull to said bow of the boat for movement within a compartment in said boat; said front hull terminating in an aft panel for supporting a power unit;

spring-damper means connected between said boat and said front hull for moving said front hull in the direction of the water supporting the boat below the hull; and

said hull being shaped to remain captive within said compartment during movement.

6. A planing boat comprising:

a front hull located at the bow of the boat and substantially less than the width of the boat;

first and second back hulls located at the rear of the boat on opposite sides of the longitudinal, vertical, center plane of the boat and extending forwardly at least as far as aft edge of said front hull;

said front and back hulls having a substantially optimum planing angle during planing to provide low drag at high speed;

said back hull having a wetted pre-planing area sufiiciently large to provide acceptable low speed displace- References Cited ment and transition drag; UNITED STATES PATENTS each of said front and back hulls having all l t 0116 1 31 339 11 1931 Brush 114 66 5 side surface sloping laterally upwardly from the 9 01 194 w n 114 6.5

bottom of the hull to the outside of the hull; 5 2,397,683 4/1946 Nelson 11466.5 said one side surface of each back hull extending for- 3,226,738 1/1966 Fox.

Wardly beyond the aft end of said front hull toward FOREIGN PATENTS Sald the mat; and 871,446 6/1961 Great Britain.

another side surface of each of said back hulls extend- 10 ing to the aft end of said front hull. ANDREW FARRELL, Primary Examiner 

